The present invention relates to an interlock assembly for use with multiple vertically arranged drawers or storage units mounted via a telescopic slide assembly in a unit such as a lateral drawer file cabinet. Specifically, the present invention relates to an interlock assembly which prevents the extension of any drawer once another drawer has been opened and which can interface with a locking system for locking all the drawers in a closed position.
Cabinets with multiple vertically arranged drawers may tilt over when more than one drawer is open at the same time, creating a hazard. The tilting of the cabinet is caused by the shifting of the cabinet center of gravity when two or more drawers are opened. Tilting of a cabinet is especially likely to occur when the open drawers contain relatively heavy materials.
To prevent such tilting, many cabinets with vertically arranged drawers incorporate interlock systems which prevent a drawer from being opened if another drawer is open. Some interlock systems in use today interface with the rear portion of the file drawers as is illustrated in U.S. Pat. No. 4,480,883. Their location makes their installation and repair difficult. Moreover, the position of such interlock mechanisms make it difficult to interface these systems with locking systems which are typically located at the front of the cabinet on either side of the top portion of the file housing.
Current interlock systems require that their components be installed or removed in a sequential order. For example, interlock components positioned between the lowermost slides must be installed prior to component located between the uppermost slides. An example of this design is an interlock mechanism utilizing a stack of latch bars as is shown in U.S. Pat. No. 4,637,667. Furthermore, components located proximate to the lowermost slides cannot be removed without first removing the components located proximate to the uppermost slides. This makes for a complex, time consuming, and costly interlock assembly installation and removal process.
In addition, most interlock assemblies in use today are designed for use with drawers of a specific height and cannot be easily altered for use with drawers of different heights.
Most interlock assemblies in use today also require that their components be built to precise tolerances. A shift in these tolerances may result in interlock assembly malfunction.
Rotational cam interlock systems are also currently in use such as are shown in PCT Application Serial No. PCT/CA93/00359 (International Publication No. WO94/07989) rely on instantaneous actuation upon drawer openings and may not always maintain a constant displacement while the drawer is open. They do not provide for a positive and maintained actuation so as to prevent system malfunction. This could result in inadvertent unlocking of the drawers. Accordingly, there is a need for an interlock assembly which can interface with the front of the slides used to couple the drawers to a cabinet or other housing and which can interface with the cabinet locking system. Moreover, an interlock assembly is needed that is easy to install, that does not require precise tolerances, and that can be easily altered for use with drawer arrangements comprising drawers of different heights.